ffr: pitfalls · aminian a et al. cci 2015 bl ffr eng. ffr diseng. 1.00 0.80 0.50 slight reduction...

9th Coronary Physiology in the CathLab Course, Nice 2015

FFR: pitfalls

Emanuele Barbato

Cardiovascular Centre Aalst, Belgium

Federico II University Naples, Italy


Pitfalls can be related to.... Preparation

• Calibration

• Equalization

Measurement

• Drifting

• Hyperaemia

• Wedging

• Whipping

Tracing interpretation

• Cursor position


Calibration


‘teaching’ the system, what is zero pressure


Setting in the cathlab


• Aortic pressure is measured by the fluid filled

guiding catheter

• Its value is a relative pressure, compared to

the reference, measured at the transducer

• Height of the transducer has a measurable

impact on the value

Calibration: Position of the Transducer


Pressure TOO LOW

Pressure TOO HIGH

Pressure OK



Calibration: PressureWire



• Fill the tube of the wire with saline



• Fill the tube of the wire with saline

• Wait a minute to have the system stabilized

• Perform calibration afterwards


Equalization


‘teaching’ the two systems, to speak the same language


Pa Pd =

Equalization


After equalization DO NOT CHANGE YOUR SETTING



• Calibration

• Equalization

Measurement

• Drifting

• Hyperaemia

• Wedging

• Whipping


• Cursor position


Drifting


When the two systems forget to speak the

same language ...


Pa Pd ≠

Post-measurement check

= Drift!!!


Drift Same morphology

Paralell shifting

Dicrotic notch well visible

True Gradient Different morphology

Dicrotic notch not visible

Drift vs Gradient ??


Hyperaemia


No hyperaemia …? … no FFR!


Wedging


Aortic pressure is inaccurately measured...


4 mm 2.4 mm 36 %

8F

4 mm 2.1 mm 27 %

7F

4 mm 1.8 mm 20 %

6F

Induced area stenosis

Size of the guiding catheter


3 mm 2.4 mm 64 %

8F

3 mm 2.1 mm 49 %

7F

3 mm 1.8 mm 36 %

6F

Size of the guiding catheter Induced

area stenosis


Wedging guiding catheter


Disengaged guiding catheter


Wedging guiding catheter

FALSE 0.88 TRUE FFR 0.66


Functional wedging of guiding catheter

Aminian A et al. CCI 2015

BL FFR eng. FFR diseng.

1.00

0.80

0.50

Slight reduction in hyperemic Pd/Pa at disengangement that with values close to the

threshold resulted into transition of 0.80 in 30% of the cases


Whipping



• Calibration

• Equalization

Measurement

• Drifting

• Hyperaemia

• Wedging

• Whipping


• Cursor position


Position the cursor to the lowest value where indeed FFR was measured


Fractional flow reserve measurement

Induce proper maximal hyperaemia

Reading the pressure tracings appropriately

Obtain accurate measurements


Thank you for your attention!

Credit for the slides to Dr. Gabor Toth and Nico Pijls


Fractional flow reserve measurement

Accurate distal coronary pressure (Pd)

Accurate aortic pressure (Pa)

Maximal hyperaemia

FFR

X X

X X


Drift vs Gradient ??

• Curves are identical in shape

• Curves are shifted paralell

• Dicrotic notch is well visible on both


Insufficient hyperaemia

Underestimation of

the gradient

Overestimation of

the FFR

Underestimation of

disease


Pressure TOO LOW

Pressure TOO HIGH

Pressure OK



Setting in the cathlab

ffr: pitfalls · aminian a et al. cci 2015 bl ffr eng. ffr diseng. 1.00 0.80 0.50 slight reduction...

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